I bought the basic Aera 500, I think there are more advanced models. The 495 offers many features not available on the Aera 500, but I expect many if not all of those features are available on the more advanced models of the Aera. There is already an Aera 500 thread running.
Generally I am very happy with the Aera 500. My only dis-satisfactions are with the automotive fuctions of the unit, not the aviation functions. I have seen in operation, but never used the 495. I did use the 295 quite a lot though, and was quite happy with it, back in the day...